Effects of Smokingonpregnancy

Maternal smoking during pregnancy is associated with decreased infant birth weight and increased incidence of prematurity, as defined by weight alone, and may be associated with an increased incidence of spontaneous abortion, stillbirth, and neonatal death. Changes in the metabolism of the placenta and in various hematological factors in the newborn infant have -been found to be associated with maternal smoking, ibut the mechanism of the effect of smoking on the outcome of pregnancy remains to be determined. New studies on the effect of maternal smoking on the outcome of pregnancy have been published since the review of this topic in the 1967 Report (12). In the 1967 review, the literature cited supported relationship between maternal smotig and low birthweight and prematurity in infants. However, the evidence relating the maternal smoking to fetal or neonatal death was not definitive. The addition of new studies has reconfirmed the relationship between maternal smoking and low birth weight and prematurity. The relationship between maternal smoking and spontaneous abortion, stillbirth, and neonatal death has been investigated in several studlies. As detailed below, some of the studies reported a statistically significant increase in unsuccessful pregnancies in mothers who smoked when compared with mothers who did not &oke.